Centrifugal forces ' appear ' to act opposite to gravity . How is this possible?

[Robittybob1]

 

Individually, or the sum. Works in a vacuum, where there would only be one force.

I looked up the definition of G-force, for I think what I will be weighing in my experiment could be a similar effect and it said G-force is not a force but a weight. Weight is what I can read on the bathroom scales. http://en.wikipedia.org/wiki/G-force

 

g-force (with g from gravitational) is a measurement of the type of acceleration that indirectly causes weight. Despite the name, it is incorrect to consider g-force a force, as "g-force" (lower case character) is a type of acceleration that can be measured with an accelerometer. Since g-force accelerations indirectly produce weight, any g-force can be described as a "weight per unit mass" (see the synonym specific weight). When the g-force acceleration is produced by the surface of one object being pushed by the surface of another object, the reaction-force to this push produces an equal and opposite weight for every unit of an object's mass.

Does G-force and centrifugal force have a similar origin? I've got to define the weights, accelerations and forces better first.

[swansont]

I looked up the definition of G-force, for I think what I will be weighing in my experiment could be a similar effect and it said G-force is not a force but a weight. Weight is what I can read on the bathroom scales. http://en.wikipedia.org/wiki/G-force

Does G-force and centrifugal force have a similar origin? I've got to define the weights, accelerations and forces better first.

 

Weight is a force. I think the subtlety here is that "g's" are accelerations, rather than forces, and measured weight is not gravity but the force pushing in the other direction when we're at rest in a gravitational field.

 

You feel a g force when you are accelerating in a car or rocket in a straight line, which have no connection to circular motion, but you could also feel this in circular motion, as the centripetal force. It's simply a convenient measurement of an acceleration, in increments of 9.8 m/s^2

 

There would be no connection to centrifugal, since the centrifugal force never acts on you, and the g-force is related to the forces acting on you. AFAICT, there has been no relevant citation of the centrifugal force in any of these threads. There is no outward force exerted on a body in circular motion. The sooner everyone accepts that simple fact and stops trying to introduce it into the conversation, the better.

[Mike Smith Cosmos]

When you lean in on the bike there is an inward component to the force on the bike, exerted by the road. If you are upright and try to turn, your inertia carrying you forward would cause your center of gravity to be outside of the bike, and you tip over.

 

Still no outward force on you, though (repeating yourself will not make you right all of the sudden). Just your tendency to go in a straight line, and the requirement that there be an inward force to move in a circle.

.

. There is no way the force is the initiative of an inward force. ( centripetal ) .At this stage the steel rails have no contact with the bike or rider. ( hopefully ) The preferred, attempted , straight line inertia, of the motorbike / me combination is the origin of the initialising outgoing force ( centrifugal ) caused by us nearing and nearly touching the ring of the circle . Only if the person ,me , driving the motor bike , decides I can not allow my legs and bike to touch the steel barriers of this curve , but rather allow the pressure to go down the bike Frame and down the wheel spokes , through the rubber tyre , to apply the pressure caused by this inertia ( must) go through the tyres to the road rather than my legs. The pressure is applied radially outwards ( Centrifugally ) through the tyre- road junction away or near the curve of the circle. At this time fighting against the natural inertia to go straight. This then invokes an equal and opposite reaction as an inward ( centripetal ) force , maybe the centripetal force is fictitious ? ( in this case) .

 

I believe this to be demonstrated by the toy lizard going up the tube by centrifugal force , invoked by the inertia of the lizard in the tube pushing outward as a force and slipping against the cardboard of the tube . Probably met by a reactive centripetal force in the circulating cardboard tube . Only when the lizard was free of the tube could the inertia cause a near straight line tangential to the exit point. Then probably meeting new constraints of gravity . ( requiring different analysis ) .

 

Mike

Edited May 13, 2015 by Mike Smith Cosmos

[swansont]

.

. There is no way the force is the initiative of an inward force. ( centripetal ) .At this stage the steel rails have no contact with the bike or rider. ( hopefully ) The preferred, attempted , straight line inertia, of the motorbike / me combination is the origin of the initialising outgoing force ( centrifugal ) caused by us nearing and nearly touching the ring of the circle . Only if the person ,me , driving the motor bike , decides I can not allow my legs and bike to touch the steel barriers of this curve , but rather allow the pressure to go down the bike Frame and down the wheel spokes , through the rubber tyre , to apply the pressure caused by this inertia ( must) go through the tyres to the road rather than my legs. The pressure is applied radially outwards ( Centrifugally ) through the tyre- road junction away or near the curve of the circle. At this time fighting against the natural inertia to go straight. This then invokes an equal and opposite reaction as an inward ( centripetal ) force , maybe the centripetal force is fictitious ? ( in this case) .

 

I believe this to be demonstrated by the toy lizard going up the tube by centrifugal force , invoked by the inertia of the lizard in the tube pushing outward as a force and slipping against the cardboard of the tube . Probably met by a reactive centripetal force in the circulating cardboard tube . Only when the lizard was free of the tube could the inertia cause a near straight line tangential to the exit point. Then probably meeting new constraints of gravity . ( requiring different analysis ) .

 

Mike

 

Nope.

 

Time to take the class over again. This is obviously not sinking in. Maybe start with Newton's laws and look at linear motion first, to clear up any conceptual problems there.

 

Did you follow the part of the discussion on forces and motion generally not being in the same direction?

[Mike Smith Cosmos]

Nope.

 

Time to take the class over again. This is obviously not sinking in. Maybe start with Newton's laws and look at linear motion first, to clear up any conceptual problems there.

 

Did you follow the part of the discussion on forces and motion generally not being in the same direction?

Well I though I did , and I was heartened that you appeared to be conceding that centrifugal forces were now a reality , that I had never heard you concede to before . But then you started saying 'nope' again . Which I did not understand .

 

This seemed to lead to robitybob saying he needed to do some experimenting ! I was doing some too, and found that things were moving out from the centre . Then you said it did not matter because it was up to where you put the base of your coordinate system . I have just been thinking conventionally with (0,0) being in the centre of any rotational system . Maybe that is where I have come adrift. If I am adrift, which I did not think I was .

 

Mike

Edited May 14, 2015 by Mike Smith Cosmos

[Robittybob1]

 

.... There would be no connection to centrifugal, since the centrifugal force never acts on you, and the g-force is related to the forces acting on you. AFAICT, there has been no relevant citation of the centrifugal force in any of these threads. There is no outward force exerted on a body in circular motion. The sooner everyone accepts that simple fact and stops trying to introduce it into the conversation, the better.

If I mount a piece of tube onto a central pivot and spun it with an electric drill. If then I stop it and insert two cylindrical masses one into each end of the mounted tube and push them right down to the pivot and then started up the drill again. Do you think the weights will be flicked out of the ends of the tubes? I didn't suggest marbles or ball bearings as they would roll too easy but these masses will take a bit of force to make them move along the tubes.

The only centripetal force would be the friction along the tube, so the "centrifugal force" only needs to overcome this resistance. Even if I tipped the tubes up at 45 degrees angles I think the masses would climb the inclines! In this alignment they would have to overcome friction and gravity.

So before I run the experiment would you care to predict what your physics allows?

Edited May 14, 2015 by Robittybob1

[swansont]

If I mount a piece of tube onto a central pivot and spun it with an electric drill. If then I stop it and insert two cylindrical masses one into each end of the mounted tube and push them right down to the pivot and then started up the drill again. Do you think the weights will be flicked out of the ends of the tubes? I didn't suggest marbles or ball bearings as they would roll too easy but these masses will take a bit of force to make them move along the tubes.

The only centripetal force would be the friction along the tube, so the "centrifugal force" only needs to overcome this resistance. Even if I tipped the tubes up at 45 degrees angles I think the masses would climb the inclines! In this alignment they would have to overcome friction and gravity.

So before I run the experiment would you care to predict what your physics allows?

 

If friction is small enough, they will move out. It is not a centrifugal force that is causing them to do so. Motion ≠ force and the motion is not radial in an inertial coordinate system.

 

Well I though I did , and I was heartened that you appeared to be conceding that centrifugal forces were now a reality , that I had never heard you concede to before .

I don't know where I conceded that centrifugal forces were ever a reality that was relevant to our discussion. I "conceded" that they are a reaction force, which means they act on other things. They do not act on the object in question.

 

If you do not understand that it is only forces acting on an object that dictate its acceleration, the we have to focus on that.

 

 

This seemed to lead to robitybob saying he needed to do some experimenting ! I was doing some too, and found that things were moving out from the centre . Then you said it did not matter because it was up to where you put the base of your coordinate system . I have just been thinking conventionally with (0,0) being in the centre of any rotational system . Maybe that is where I have come adrift. If I am adrift, which I did not think I was .

 

Mike

Motion ≠ force

[Mike Smith Cosmos]

If friction is small enough, they will move out. It is not a centrifugal force that is causing them to do so. Motion ≠ force and the motion is not radial in an inertial coordinate system.

 

 

I don't know where I conceded that centrifugal forces were ever a reality that was relevant to our discussion. I "conceded" that they are a reaction force, which means they act on other things. They do not act on the object in question.

If you do not understand that it is only forces acting on an object that dictate its acceleration, the we have to focus on that.

 

 

Motion ≠ force

.

 

. Is there such a thing as :-

 

a) Centrifugal Motion B) Inertial Force C ) Centrifugal Force ( anywhere) ?

D) Something traveling up the radius not be called Radial . E) if I come across what looks remarkable like a Force, making something move out along a radius , can I not call it a Centrifugal Force? If not, why not ?

 

And would you kindly mind telling all the persons you are aware of , to not keep loading me with all these NEGATIVE. REPUTATION POINTS . This is a DISCUSSION FORUM not a WAR ZONE !

 

If you are trying to wipe me out , kindly do it honourably . Thank you . And kindly reinstate my rep points .

 

Mike

Edited May 14, 2015 by Mike Smith Cosmos

[imatfaal]

....

And would you kindly mind telling all the persons you are aware of , to not keep loading me with all these NEGATIVE. REPUTATION POINTS . This is a DISCUSSION FORUM not a WAR ZONE !

 

If you are trying to wipe me out , kindly do it honourably . Thank you . And kindly reinstate my rep points .

 

Mike

 

I hadn't got around to neg-repping your last post yet - but I will explain my thinking; you are clearly ignoring any arguments that do not accord with your preconceptions. Your strong assertions in the neg-repped post were countered 16 pages ago - and months ago in other threads. If you cannot be bothered to treat other's opnions as worthy of consideration (I cannot believe you explored them and the physics background and still hold the views you do) then why are you on a discussion forum? We do not reinstate rep points - they are the gift and sanction of the members; perhaps take into consideration why so many members thought your post worthy of rebuke.

[swansont]

.

 

. Is there such a thing as :-

 

a) Centrifugal Motion B) Inertial Force C ) Centrifugal Force ( anywhere) ?

D) Something traveling up the radius not be called Radial . E) if I come across what looks remarkable like a Force, making something move out along a radius , can I not call it a Centrifugal Force? If not, why not ?

 

 

A) Yes

B) No, inertia is inertia and force is force.

C) Anywhere? Yes, but in the context of this discussion it is irrelevant.

D) Yes

E) No, not in any meaningful way, because words have definitions.

 

You can call your coffee cup a fork, but that doesn't mean it's actually a fork. If you start mis-using terminology, all you do is cause confusion.

[DrP]

Yea - you seem like a nice bloke Mike.... maybe that is why you got the positive rep you have currently. But it is important that strangers, new comers and young people don't actually believe your side of many of the arguments you put across because they are just wrong. If you state something that is complete rubbish as a fact and argue it over and over against half a dozen other people who are respected members here and know what they are talking about..... then it is important that people do not think that what you are saying is true... thus the neg rep, people can see it and know that what you are saying might not actually right. ;-) Sorry - nothing personal, but after you have been going in circles for the last 16 pages I added a -1 point to your above post. Rightly imo. Have a nice day.

 

What level of training do have as a scientist by the way? Do you think you should have a high reputation in the field of science due to your knowledge experience and education?

[tar]

SwansonT,

 

While I understand we cannot call outward motion the result of a radially outward directed force that does not exist, your answer to question c, that the fact that outward motion is felt or observed IS the discussion, as we are trying to understand why one feels this outward pressure, and why the lizard moves to the end of the tube, and why my clay ball on a pick tipped outward.

 

I think Mike and I and RobbittyBob1 are trying to ask a different question than you are answering from time to time. And it is slightly unfair, in a speculation forum to not allow speculation.

 

For instance, when I asked Janus for a rendering of what the picture would look like from a circulation frame, and what it would look like from a inertial frame, several periods later, no one made a comment. So I do not know if people ran this thought experiment in their head, or not. I do not know what people thought about my earlier consideration that tangential motion from a very small circle, looks like radial motion from a point.

 

The tube idea is good thought experiment tool, because it IS a radial line. If an object moves out from the center, along this tube, it has to be moving in a radially outward direction in one reference frame or the other, or at least in reference to the radial line embodied by the tube.

 

There is no force ON an object moving it radially outward, but the object, through its inertia was never interested in moving in a circle in the first place. An object is only interested in staying still. An object likes to move at a constant velocity in a straight line, even if that velocity is zero. Disturbing an object from its rest, or straight line motion, takes a force.

 

In the case of the roundabout the kid wants to stay still when the round about start to spin. His head stays behind a radial line and he draws it in line with the radial with his muscles, informed as to which direction is up, by the position of the fluid, in his inner ears. By looking at individuals on a rapidly spinning round about, one can see the direction their bodies think is up, is the center of the round about, as their heads are bowed with the crown of their heads facing the center.

 

The motor bike rider also has fluid in her inner ears informing her of which way is up, and which way she has to lean to keep from tipping over.

 

The kid on the round about, and the motor bike rider "feel" like the top of their head, should be oriented upward, in a direction which is counter to gravity in normal situations and is counter some other pull in the round about and motorbike on a curve situation. This "other pull" is what Mike and I and RobittyBob1 are speculating about. We all three have conceeded that there is no radially outward force, as you all have carefully defined force as what would be required to accelerate a mass.

 

The thread question is why centrifugal forces appear to act opposite gravity. This question is instantly identified as a bad question, since there is no such thing as a centrifugal force, except there is such thing as reactive centrifugal force, and there is such thing as artifical gravity, created by using the axis of rotation of a space ship to be "up" in the direction opposite the pull of the artificial gravity. In the spaceship example, with the artifical gravity the downward pull of the artificial gravity, is toward the outside circumference of the ship. This is a radially outward fictious force generated somehow by the inertia of the spaceperson.

 

In Janus' renderings, the motions ceased to be circular, the instant the ship no longer had its tail in its mouth. What was the center was being retreated from, by all components in a direction parallel to a radial line, one radius away. After 1000 periods, the components would be distributed in a circle, with the original center, still the center. They would not have proceeded exactly radially outward...but close enough for government work.

 

Regards, TAR

[swansont]

SwansonT,

 

While I understand we cannot call outward motion the result of a radially outward directed force that does not exist, your answer to question c, that the fact that outward motion is felt or observed IS the discussion, as we are trying to understand why one feels this outward pressure, and why the lizard moves to the end of the tube, and why my clay ball on a pick tipped outward.

You (collectively) are, for the most part, not acting like you are trying to understand this, when you continue to insist the there is an outward force. Repeating the wrong answer as a response to correction is not consistent with that position.

 

You can try to ask questions without insisting something is true (when it is in fact false), or ask for clarification of answers that have been given.

 

I think Mike and I and RobbittyBob1 are trying to ask a different question than you are answering from time to time. And it is slightly unfair, in a speculation forum to not allow speculation.

What is acceptable as speculation is defined reasonably well (IMO) in our guidelines. What we don't allow is WAG-ing, or attempts at proof by repetition. Further, this is well-established physics. There is no reason that I can see to speculate in the first place. Nobody has broached any kind of potential flaw in standard physics that would require new physics to be developed.

 

For instance, when I asked Janus for a rendering of what the picture would look like from a circulation frame, and what it would look like from a inertial frame, several periods later, no one made a comment. So I do not know if people ran this thought experiment in their head, or not. I do not know what people thought about my earlier consideration that tangential motion from a very small circle, looks like radial motion from a point.

I have posted descriptions and a diagram of what motion looks like from the inertial frame, for one of the examples. People have posted videos of what motion looks like in the rotating frame. So please don't insist that nobody has done this. Perhaps your particular example was not addressed, but that's part of a larger problem of ignoring the simple picture and complicating it. The basic physics, and answer, will not change. I don't know from where the optimism arises that if you add enough caveats to a problem that suddenly physics will change.

 

 

The tube idea is good thought experiment tool, because it IS a radial line. If an object moves out from the center, along this tube, it has to be moving in a radially outward direction in one reference frame or the other, or at least in reference to the radial line embodied by the tube.

Another example of why we need to go back to the equivalent of the first week of physics and talk about the underlying basics, so you can see why this is wrong. The idea here is that Newton's first law tells you you have to use inertial coordinate systems in order to apply Newton's second law, and in doing so, you find that the motion is not radial. (i.e. not solely in the r direction)

 

 

There is no force ON an object moving it radially outward, but the object, through its inertia was never interested in moving in a circle in the first place. An object is only interested in staying still. An object likes to move at a constant velocity in a straight line, even if that velocity is zero. Disturbing an object from its rest, or straight line motion, takes a force.

Yes, precisely.

 

We all three have conceeded that there is no radially outward force, as you all have carefully defined force as what would be required to accelerate a mass.

I am not going to go through the exercise of pointing out the many times this claim is falsified.

 

The thread question is why centrifugal forces appear to act opposite gravity.

Once we get past the point of folks insisting that there is such a force on the object, maybe we can get to that, though the answer has already been given several times.

[Strange]

While I understand we cannot call outward motion the result of a radially outward directed force that does not exist, your answer to question c, that the fact that outward motion is felt or observed IS the discussion, as we are trying to understand why one feels this outward pressure, and why the lizard moves to the end of the tube, and why my clay ball on a pick tipped outward.

 

That has been explained repeatedly and at great length by many people in several different ways.

 

I think Mike and I and RobbittyBob1 are trying to ask a different question than you are answering from time to time. And it is slightly unfair, in a speculation forum to not allow speculation.

 

There is nothing to speculate about. This is basic, schoolboy physics.

 

For instance, when I asked Janus for a rendering of what the picture would look like from a circulation frame, and what it would look like from a inertial frame, several periods later, no one made a comment.

There was an excellent YouTube video (in one of the many other threads on essentially the same subject) showing the paths taken by a ball thrown in a rotating frame, as seen from each frame of reference.

 

I can't find exactly what you are asking for, but this is close:

http://www.edcoogle.com/question/1033/why-is-the-centripetal-force-called-a-pseudo-force

[tar]

Mike,

 

Someone suggested that if you put a marble in a vertical tube, you should not expect it to rise upward. We already know this is true. After all the inertia of the tube and the marble are pretty much matched. The rotation of the Earth is not a new thing, for either the tube or the marble.

 

 

From the Wiki article on Coriolis Effect;

"The Coriolis force acts in a direction perpendicular to the rotation axis and to the velocity of the body in the rotating frame and is proportional to the object's speed in the rotating frame. The centrifugal force acts outwards in the radial direction and is proportional to the distance of the body from the axis of the rotating frame. These additional forces are termed inertial forces, fictitious forces or pseudo forces.^[1] They allow the application of Newton's laws to a rotating system. They are correction factors that do not exist in a non-accelerating or inertial reference frame."

 

In your muses you visulize somehow tapping into these inertial forces, as a source of energy. What is important to everybody here, giving us neg reps is that you use the laws of physics, and the already well defined F=ma to guide your speculations. If you suck energy out of an inertial body you would have changed something about the body. Its inertia would be different, for one.

 

Regards, TAR

[swansont]

These additional forces are termed inertial forces, fictitious forces or pseudo forces.^[1] They allow the application of Newton's laws to a rotating system. They are correction factors that do not exist in a non-accelerating or inertial reference frame.

 

 

Re-iterating and bolding for emphasis.

 

IOW, they are a correction to try and let you use Newton's laws in a situation where Newton's laws do not work. They are not real.

[Mike Smith Cosmos]

A) Yes

B) No, inertia is inertia and force is force.

C) Anywhere? Yes, but in the context of this discussion it is irrelevant.

D) Yes

E) No, not in any meaningful way, because words have definitions.

 

You can call your coffee cup a fork, but that doesn't mean it's actually a fork. If you start mis-using terminology, all you do is cause confusion.

You appear to agree to C) , that there are places where Centrifugal Forces exist .

 

As a genuine researcher , keen on seeing if there is any possible chance that Centrifugal force can fit anywhere in association with gravity . Why can I not develop an exploratory discussion which pursues these matters. This particularly as some of the immediate evidence "appears" as if there does appear to exist , such an outgoing force.

 

Why does there have to be a call for all this, " this is kiddies physics" and all the other copious other remarks and negative reputation points which have nothing positive to offer to the subject . I am a genuine person , and expect to be spoken and dealt with to in a friendly, not hostile , not provocative manner . And certainly not in a ' bullying style ' more reminiscent of back street intimidation and hurt. If I say something that is wrong . Why can't you just say " that is wrong " not invoke a tirade of negative rep points.

 

Mike

Edited May 14, 2015 by Mike Smith Cosmos

[tar]

Strange,

 

Thank you for the videos. I already get those explanations. The question though, for me, is not what forces are present, but the position of the ball on the end of the rope hanging vertically down from the bar on the merry go round. It is outside the circumference of the bar, and lifts further out, as you speed up the rotation. Looking at the circle from above, you could draw a radial line from the center to the point where the rope is attached, and the rope that the ball was on would be slightly behind this radial line, getting closer and closer to radial as the thing sped up. Its the inertia of the ball, that is the interesting thing to me.

 

The 8 ball does go off in a tangent, as we all already conceed. But I goes off to the left and down, or to the right, or up and to the left, depending on when the ring is lifted. The thought experiment I am asking people to make, is to zoom away from the ring and visualize the ring lifted every 15 degrees, as the ball is at 12 o'clock, 12:30, 1:00...etc. The tracks of the balls will be straight lines, each one tangential to the circle, and going off in a direction normal to the hour hand at 12 o'clock, but in exactly the same direction, and parallel to the hour hand at 3 o'clock. (when the ring is lifted at the 12 o'clock position.) When looking at the experiment from 10,000 ft. in the air, the balls are traveling off in exactly the radial direction, along the lines pointed in the direction of at 12, 12:30, 1, 1:30...

 

Regards, TAR

This I find important to the discussion, because, on the playground it feels like you are being pulled outward as your arms are extended like the rope, and your body and head the ball at the end of the pendulum in the video, and when four kids jump off from four corners of the thing at the same time, they end up away from the center, all the same radial distance.

[swansont]

You appear to agree to C) , that there are places where Centrifugal Forces exist .

 

As a genuine researcher , keen on seeing if there is any possible chance that Centrifugal force can fit anywhere in association with gravity . Why can I not develop an exploratory discussion which pursues these matters. This particularly as some of the immediate evidence "appears" as if there does appear to exist , such a outgoing force.

 

 

There is no situation under discussion here or in related threads where there is a centrifugal force acting on the object. This is, in fact, very basic physics.

 

It is exceedingly likely that your insistence that you are right in the face of this basic physics is the source of your negative votes. This is like a student who was insisting that 2+2=5. "Stubbornly hanging on to a conceptual error is not endearing" is the message here.

Strange,

 

Thank you for the videos. I already get those explanations. The question though, for me, is not what forces are present, but the position of the ball on the end of the rope hanging vertically down from the bar on the merry go round. It is outside the circumference of the bar, and lifts further out, as you speed up the rotation. Looking at the circle from above, you could draw a radial line from the center to the point where the rope is attached, and the rope that the ball was on would be slightly behind this radial line, getting closer and closer to radial as the thing sped up. Its the inertia of the ball, that is the interesting thing to me.

That can be analyzed. What exactly is the issue? There is tension and air resistance. It's not clear the lagging angle (angle behind the radial line) would change, since air resistance generally tracks with v^2, and the centripetal force also varies as v^2.

 

The 8 ball does go off in a tangent, as we all already conceed. But I goes off to the left and down, or to the right, or up and to the left, depending on when the ring is lifted. The thought experiment I am asking people to make, is to zoom away from the ring and visualize the ring lifted every 15 degrees, as the ball is at 12 o'clock, 12:30, 1:00...etc. The tracks of the balls will be straight lines, each one tangential to the circle, and going off in a direction normal to the hour hand at 12 o'clock, but in exactly the same direction, and parallel to the hour hand at 3 o'clock. (when the ring is lifted at the 12 o'clock position.) When looking at the experiment from 10,000 ft. in the air, the balls are traveling off in exactly the radial direction, along the lines pointed in the direction of at 12, 12:30, 1, 1:30...

The tangential line is parallel to a radial line at a different angle. So?

[tar]

Strange,

 

In the 8 ball video. Watch how the guy gets the ball going. He hits the ball with the ring then turns the ball by placing the curved ring in its way to guide it and pushes the ball with the back of the curve, moving the ring in a circular motion. Interesting to investigate the forces being applied to the ball to get its inertia going. I would speculate that they would add up to tangential/radial outward vectors, that would counter the inward, centripedal forces.

 

 

So while the ball is being coaxed into a circle, by a net centripedal force. The ball was coaxed into motion in the first place, by a net outward force. On the playground the merry go round got going by pushers running round in a circle. As the thing got going faster than the pushers could run, the pushers stopped and swiped at the vertical bars, imparting a tangential, or outward force to the the passing bar.

 

Regards, TAR

[swansont]

Strange,

 

In the 8 ball video. Watch how the guy gets the ball going. He hits the ball with the ring then turns the ball by placing the curved ring in its way to guide it and pushes the ball with the back of the curve, moving the ring in a circular motion. Interesting to investigate the forces being applied to the ball to get its inertia going. I would speculate that they would add up to tangential/radial outward vectors, that would counter the inward, centripedal forces.

 

 

So while the ball is being coaxed into a circle, by a net centripedal force. The ball was coaxed into motion in the first place, by a net outward force. On the playground the merry go round got going by pushers running round in a circle. As the thing got going faster than the pushers could run, the pushers stopped and swiped at the vertical bars, imparting a tangential, or outward force to the the passing bar.

 

Regards, TAR

The centripetal or hypothetical centrifugal force cannot be responsible, because they are perpendicular to the circular motion and do no work on the ball. If this was purely circular motion, that is, which it isn't. Which means it's moot, because the ball isn't moving in a circle while he's moving the form around.

 

However, if the circle were fixed, it would only speed up or slow down due to a tangential force.

[tar]

SwansonT,

 

You keep insisting that I don't get it.

 

I have already conceeded that there is, by definition, no radially outward force.

 

I am continuing the discussion on the basis of the real effects of the inertia a body has, and the forces that needed to be applied to give that body its inertia.

 

The interesting thing about a circle is that you could get the merry go round spinning in one direction, by standing outside its circumference and pulling a vertical bar on your right toward you, and away from you to the left. If you were standing at 6 oclock you exerted a net force toward 9 o'clock. At any point however you were pushing some part of the merrygoround and its inhabitants in all directions. All the tangents to the circle move away from the circumference. When you pushed toward 9 o'clock, that made the person at 12 head for three. Always heading away from the center, as the centripedal forces were keeping the inhabitants headed for the center.

 

In Janus' renderings, the positions after the breakup where in an arc left for one frame and in a straight line right for the other.

In my start and stop spinning of the clay ball on the top of a pick, I felt the inertia of the ball, trying to stay stationary as I started and trying to keep going in a straight line when the friction of the clay against the pen slowed the clay disc.

 

The combined inertial effects. That of wanting to stay still, and that of wanting to keep going in a straight line, caused and outward motion. No force going in that direction but fictious ones, apparent ones, and reactionary ones but that does not mean the results are not real.

 

I think perhaps we have a philosophical disagreement here, not a disagreement over the facts.

 

Regards, TAR

Besides, according to the third law a reactionary centrifugal force, to the centripedal force, is a requirement. Apparent, convenient, fictitious or not, we can still talk about it.

Let me ask a question though.

 

If a force is not required to keep a body in motion, is a force required to get a body into motion?

 

I am considering motion to be motion in a straight line, within an inertial reference frame.

Secondary question. If a system like the Earth has everything moving together on its surface in a circle around its axis and the Earth is moving around the Sun, and the Sun around the Milkyway's center, where would one find an inertial frame to investigate?

 

Isn't everything in orbit around something?

Edited May 14, 2015 by tar

[Strange]

When looking at the experiment from 10,000 ft. in the air, the balls are traveling off in exactly the radial direction, along the lines pointed in the direction of at 12, 12:30, 1, 1:30...

 

They are not travelling exactly in the radial direction. The line that is tangent to the circle may be parallel to a radial line (and never meet it) or be at some other angle (depending which radial direction you choose). But they can never be the same because they start from different points.

Interesting to investigate the forces being applied to the ball to get its inertia going. I would speculate that they would add up to tangential/radial outward vectors, that would counter the inward, centripedal forces.

 

I don't see how the force could sum to an outward direction as the ring is always outside the ball, and therefore the forces are always inwards. (Which is the answer to 90% of the questions in this thread!)

Why does there have to be a call for all this, " this is kiddies physics" and all the other copious other remarks and negative reputation points which have nothing positive to offer to the subject . I am a genuine person , and expect to be spoken and dealt with to in a friendly, not hostile , not provocative manner . And certainly not in a ' bullying style ' more reminiscent of back street intimidation and hurt. If I say something that is wrong . Why can't you just say " that is wrong " not invoke a tirade of negative rep points.

 

The negative points are not for being wrong (otherwise you would have an even larger number ) but for refusing to accept you are wrong, refusing to understand how you are wrong, for remaining wilfully ignorant of basic(sorry) physics.

[swansont]

SwansonT,

 

You keep insisting that I don't get it.

I have asked you what your point is and discussed work in the last two posts. i.e. addressing your questions.

 

 

I have already conceeded that there is, by definition, no radially outward force.

Great. I thought we had moved on from this.

 

 

I am continuing the discussion on the basis of the real effects of the inertia a body has, and the forces that needed to be applied to give that body its inertia.

Which was the topic of my last post. A tangential force is required. Radial forces do no work on an object moving in a circle.

 

 

The interesting thing about a circle is that you could get the merry go round spinning in one direction, by standing outside its circumference and pulling a vertical bar on your right toward you, and away from you to the left. If you were standing at 6 oclock you exerted a net force toward 9 o'clock. At any point however you were pushing some part of the merrygoround and its inhabitants in all directions. All the tangents to the circle move away from the circumference. When you pushed toward 9 o'clock, that made the person at 12 head for three. Always heading away from the center, as the centripedal forces were keeping the inhabitants headed for the center.

And again I ask what the point is of this observation.

 

Centripetal motion does not have the object head toward the center, they have objects accelerate toward the center. position ≠ velocity ≠ acceleration

 

 

In Janus' renderings, the positions after the breakup where in an arc left for one frame and in a straight line right for the other.

In my start and stop spinning of the clay ball on the top of a pick, I felt the inertia of the ball, trying to stay stationary as I started and trying to keep going in a straight line when the friction of the clay against the pen slowed the clay disc.

 

The combined inertial effects. That of wanting to stay still, and that of wanting to keep going in a straight line, caused and outward motion. No force going in that direction but fictious ones, apparent ones, and reactionary ones but that does not mean the results are not real.

We remove the need for fictitious forces by analyzing the motion in an inertial frame, which allows us to apply Newton's laws unburdened by the distractions of unicorns.

 

 

Besides, according to the third law a reactionary centrifugal force, to the centripedal force, is a requirement. Apparent, convenient, fictitious or not, we can still talk about it.

But it has no effect on the motion of an object, since it does not act on the object. i.e. reaction forces are irrelevant to the discussion, as I have pointed out numerous times.

 

 

Let me ask a question though.

 

If a force is not required to keep a body in motion, is a force required to get a body into motion?

 

I am considering motion to be motion in a straight line, within an inertial reference frame.

Newton's first law tells us that to change the state of linear motion requires a force.

 

 

Secondary question. If a system like the Earth has everything moving together on its surface in a circle around its axis and the Earth is moving around the Sun, and the Sun around the Milkyway's center, where would one find an inertial frame to investigate?

 

Isn't everything in orbit around something?

Yes. We use approximations, because the degree to which a frame is not inertial can be estimated. The effect of rotation of the earth has a negligible effect on the trajectory of a baseball traveling 100 meters over the course of a few seconds, but cannot be ignored for the trajectory of a faster ballistic object over a longer path, since the effect scales with speed, and depends on the earth rotation rate (somewhere around 10^-4 s^-1), and the deflection integrates over time. A baseball deflecting a mm is not a big deal and can be ignored. A naval barrage deflecting by meters can't be.

[Robittybob1]

 

If friction is small enough, they will move out. It is not a centrifugal force that is causing them to do so. Motion ≠ force and the motion is not radial in an inertial coordinate system. ....

 

Motion ≠ force

Thanks, so we are both expecting the same thing in that the mass will move along the tubes and be thrown out in a direction that is a combination of their tangential speed and the speed they climbed the tube. We might be able to see that direction during the experiment.

So to stop the ball rising in the tube we would have to apply a force to stop that motion wouldn't we? What would you called that force? If it was a piece of string you might call it a centripetal force. If you blocked the end of the tube you might call it a normal force. These forces are acting against an opposing force. Those masses wont travel in a circle unless there is a sufficient centripetal force. So when we say they are thrown out by centrifugal force but is it just centrifugal motion?